Re: [PATCH v2 3/4] sequencer: refactor the code to detach HEAD to checkout.c

Pratik Karki [off-list ref] writes:

The motivation behind this commit is to extract the core part of
do_reset() from sequencer.c and move it to a new detach_head_to()
function in checkout.c.

Here the index only gets locked after performing the first part of
`do_reset()` rather than before which essentially derives the `oid`
from the specified label/name passed to the `do_reset()` function.
It also fixes two bugs: there were two `return error()` statements in
the `[new root]` case that would have failed to unlock the index.

The new function will be used in the next commit by the builtin rebase,
to perform the initial checkout.

I like the split of do_reset() into this "detach-to" part that is
less specific to replaying an existing commit and the rest, which
as you said incidentally corrects the locking issue.

It is not clear to me why checkout.[ch] is a better place to house
this function, though.